Apparatus for stabilized transport of web-or sheet-like materials



S. WALLlN Sept. 13, 1966 APPARATUS FOR STABILIZED TRANSPORT OF WEB- 0RSHEETLIKE MATERIALS Filed March 16, 1964 FIGI.

mvam'onz SVEN WA LLI N United States Patent 3,272,415 APPARATUS FORSTABILIZED TRANSPORT ()F WEB- OR SHEET-LIKE MATERIALS Sven Wallin, Taby,Sweden, assignor to Alrtiebolaget Svenska Flaktfabriken, Stockholm,Sweden Filed Mar. 16, 1964, Ser. No. 352,721 Claims priority,application Sweden, Mar. 17, 1963, 3,004/63 8 Claims. (Cl. 226-97) Thisapplication is a continuation-in-part of the application of thisinventor, Sven Wallin, Serial No. 289,467, filed on June 19, 1963, nowPatent No. 3,206,092, dated September 14, 1965, and claiming priorityfrom an earlier filed Swedish application dated June 21, 1962.

The present invention relates to an apparatus for stabilized transportof a sheet-like material such as a web which is supported by means ofair or other gaseous medium.

In the present instance the apparatus comprises a plurality ofdistribution ducts for supplying the medium, these ducts having asurface facing the material forming a guide plane for the material andprovided with a plurality of medium supply ports, arranged in pairs andprimarily directed in opposite directions. Typically, the supply portsare arranged having the shape of pressed-down eye-lid perforations, andconstructed so that the medium is caused to flow from these in streamsessentially parallel to the plane of the transported material. Further,exhaust ducts having exhaust ports are also arranged in the guide planeacting in conjunction with the supply ports in order to extract themedium from the space between the material and the plane. The inventionis intended to provide an improvement of recently-produced apparatus ofthe kind based on the principle or concept that the flow or venturieffect, which principle states that when a gaseous medium flows betweentwo surfaces, a force will be exerted which will tend to move thesesurfaces towards each other, can be utilized to produce a stabilizedcarrier with the material floating without tension at a fixed distancefrom the guide plane.

In previously known apparatus the medium is supplied by means of anumber of distribution boxes presenting one side facing the web ofmaterial and located on the transport plane, each provided with rows ofdischarge ports grouped along the centre line of the box and with thespace between the boxes acting as exhaust ducts for the medium.

The invention, which is based on the concept that the application of theeffect is not limited by the above-mentioned constructional shape of thedistribution elements, is characterized in that the supply and exhaustopenings are arranged in relation to each other so that the mediumsupplied therefrom has time to form a continuous film of medium beforebeing exhausted. Further, as the medium is being extracted it is dividedup into a number of separate streams.

The invention will permit a choice of location of both supply ports formedium supply and exhaust ports for its extraction. Thus, for example, aplurality of supply ports can be arranged in one and the samedistribution duct while in the same way the exhaust ports may be locatedbetween the supply ports assuming that the conditions set forth aboveare fulfilled. In order to ensure that the material is not acted upon ina disturbing manner by the medium leaving through the exhaust ports,according to a suitable embodiment of the invention, the total area ofthe exhaust ducts may constitute between 20 times, preferably 10 times,the total area of the supply ports to ensure that extraction takes placewithout the generation of a difference in static pressure on the mediumon both sides of the material. This permits a fixed position of thematerial in relation to the guide plane. For the same reason, accordingto a second suitable embodiment of the invention, the exhaust ducts areprovided with a grating, in which the area of free flow constitutes50-90% of the areas of the exhaust ducts and the remaining part of thegrating forms the supporting plane for transmitting two streams ofmedium directed towards each other so that the said streams form a filmof medium along the centre part of the grating stably supporting thematerial. These gratings may be designed in the shape of an are or madeconvex.

The invention may also be utilized for stabilizing a webor sheet-likematerial which is driven forward by mechanical conveyors or airbornethrough a plant with air distribution elements of other design, in thatthe material on a part of the transport path is carried over a separatedistribution duct constructed according to the invention. In a similarmanner the invention may be used in applications where transport is totake place vertically or at an angle inclined to the horizontal plane.In that instance the distribution ducts may be located on an arbitraryside of the material, such as, if suitable, above the material. Due tothe fact that the material transported according to the invention willbe driven completely without tension, the utilization of the inventionin, eg dryers for paper, means that the finished product will possessexcellent values as regards longitudinal elongation, transverseelongation and strength.

Other objects and a fuller understanding of the invention may be had byreferring to the following specification and claims taken in conjunctionwith the accompanying drawing in which:

FIG. 1 is a fragmentary perspective view of a portion of apparatusconstructed in accordance with the present invention;

FIG. 2 is a perspective view of another embodiment of the presentinvention; and

FIG. 3 is a fragmentary perspective view of another embodiment ofapparatus constructed according to the invention.

In the drawing, a web-like material 1 is driven forward above atransport or guide plane comprising a plurality of air distributionducts 2, which supply air or other gaseous medium from supply means, inthe present instance fans (not shown). In the surface 2a of the ducts 2facing the material, are gaseous medium supply ports 3a and 3brespectively, made, in the present instance in the form of pressed-downeye-lid perforations directed principally in opposite directions andconstructed so that the medium is caused to flow substantially inopposite directions in streams essentially parallel to the transportplane. As illustrated, the ports 3a of one row are staggered withrespect to the ports 3b of the other row. The medium is extractedthrough exhaust ducts 4 located so as to prevent collision between theundivided streams of medium before being exhausted. In order to complywith this condition, the distance between supply ports and correspondingexhaust ducts should be such that the velocity of the stream of mediumin the space between material and transport plane is reduced to 0.2-0.8times, preferably 0.5 times, the medium supply velocity. Gratings 5arranged in the exhaust ducts are provided with exhaust ports 6, thetotal area of which amounts to 5090% of the exhaust duct area. In thecase shown in FIG. 1, where the distribution ducts are provided withbevelled edges 7, the grating 5 has been made in the shape of an arc inorder to obtain an unaltered level for the material.

FIG. 2 illustrates another embodiment of the invention with the web ofmaterial removed. In this embodiment a plurality of ducts 12 havingsurfaces 12a and 12b are provided with gaseous medium supply ports 13and 23 respectively. For purposes of identification, the ports 13 havebeen designated as rows, 13a and 13b while the ports 23 have beendesignated as rows 23a and 23b. Although the eye-shaped ports 23 and 13are somewhat dissimilar they serve the same function as the ports 3a and3b as heretofore described. Further, as may be noted in FIG. 2, thecorresponding rows of ports are aligned and not staggered as thoseillustrated in FIG. 1. In a manner similar to that above-described, themedium is extracted through exhaust du-cts 14 having gratings 15 andexhaust ports 16 therein, and positioned with respect to the supplyports so as to prevent collision between the undivided streams of mediumas it flows therebetween. The various limits as to distance, area andvelocity are as heretofore described.

In the embodiment shown in FIG. 3, a plurality of gaseous medium supplyports 8a, 8b, are arranged in one and the same distribution duct 9, andthe exhaust ports are located in this instance between the supply portsand are connected to an exhaust duct through passages 11.

As distinguished from earlier known transport apparatus, where thematerial is supported by jets of air at right angles to it, theinvention may be used to transport materials with great differences inarea per weight without any ditficulties whatsoever in producing thedesired material level.

Without departing from the concept of the invention, the distributionducts could be arranged so that they combine to form an arched transportplane or a plane following an arbitrary arc.

What I claim is:

1. Apparatus for the stabilized transport of web or sheet, like materialsupported by a gaseous medium, said apparatus comprising: at least onedistribution duct for supplying said medium, said duct having a surfaceconfronting said material and forming a guide plane therefor, gaseousmedium supply ports arranged in pairs in said plane and each port of apair directed oppositely to the other port of the pair, said supplyports including means whereby said medium is caused to flow therefrom instreams substantially parallel to said transport plane, exhaust ports insaid guide plane spaced from the acting in conjunction with said supplyports to extract the medium from the space between said material andsaid plane, said supply and exhaust ports being positioned in relationto each other so that the medium supplied from said supply ports forms acontinuous film of medium prior to being exhausted through said exhaustports, and means to divide said continuous film into a plurality ofseparate streams upon being exhausted.

2. Apparatus in accordance with claim 1 including a plurality ofdistribution ducts arranged transverse to the direction of transport ofsaid material, and wherein said supply ports are located along thecenterline of said ducts, said ducts being spaced one from the other inthe direction of transport so as to define exhaust ducts therebetween,

and a grating covering said exhaust duct, said grating including saidexhaust ports.

3. Apparatus in accordance with claim 1 wherein said guide planecomprises a continuous medium distribution duct having equally spacedrows of supply ports substantially transverse to the direction ofmaterial transport, and wherein said exhaust ports are separate portsand pass through said distribution duct, said exhaust ports locatedadjacent each other and arranged in rows parallel to said supply ports.

4. Apparatus in accordance with claim 3 where-in said rows of exhaustports lie transverse to the direction of material transport and arelaterally alternating with said supply ports.

5. Apparatus in accordance with claim 1 wherein the area of said exhaustports is five to twenty times the total area of said supply portsthereby insuring extraction of said medium without generation ofdifferences in static pressure of the medium on both sides of thematerial thereby allowing the material to be fixedly located relative tosaid transport plane.

6. Apparatus in accordance with claim 5 wherein said total area of theexhaust ports is ten times the total are-a of said supply ports.

7. Apparatus in accordance with claim 1 including at least two supplyducts spaced from each other so as to define an exhaust ducttherebetween, and wherein said surface confronting said material andforming a guide plane therefor includes a transverse bevel to impart adeviation from the surface of the material being conveyed, said exhaustduct having a grating defining said exhaust ports and an intermediateportion between said ports, the area of said exhaust ports being atleast 50 to percent of the cross section-a1 area of said exhaust ductwhereby the said 7 intermediate portion of said grating forms thesupporting plane for transmitting two streams of medium directly towardseach other so that the said streams form a pressurized cushion stablysupporting the material along the center portion of said grating.

8. Apparatus in accordance with claim 7 wherein said grating over saidexhaust ducts is outwardly convex in cross section.

References Cited by the Examiner UNITED STATES PATENTS 713,787 11/1902McKone 30231 2,848,820 8/1958 Wallin et al. 22697 X 2,905,768 9/1959Cronquist. 3,070,901 1/ 1963 Allander et al. 3,206,092 9/1965 Wallin22697 FOREIGN PATENTS 945,309 12/ 1963 Great Britain.

M. HENSON WOOD JR., Primary Examiner.

A. N. KNOWLES, Assistant Examiner.

1. APPARATUS FOR THE STABILIZED TRANSPORT OF WEB OR SHEET LIKE MATERIALSUPPORTED BY A GASEOUS MEDIUM, SAID APPARATUS COMPRISING: AT LEAST ONEDISTRIBUTION DUCT FOR SUPPLYING SAID MEDIUM, SAID DUCT HAVING A SURFACECONFRONTING SAID MATERIAL AND FORMING A GUIDE PLANE THEREFOR, GASEOUSMEDIUM SUPPLY PORTS ARRANGED IN PAIRS IN SAID PLANE AND EACH PORT OF APAIR DIRECTED OPPOSITELY TO THE OTHER PORT OF THE PAIR, SAID SUPPLYPORTS INCLUDING MEANS WHEREBY SAID MEDIUM IS CAUSED TO FLOW THEREFROM INSTREAMS SUBSTANTIALLY PARALLEL TO SAID TRANSPORT PLANE, EXHAUST PORTS INSAID GUIDE PLANE SPACED FROM THE ACTING IN CONJUNCTION WITH SAID SUPPLYPORTS TO EXTRACT THE MEDIUM FROM THE SPACE BETWEEN SAID MATERIAL ANDSAID PLANE, SAID SUPPLY AND EXHAUST PORTS BEING POSITIONED IN RELATIONTO EACH OTHER SO THAT THE MEDIUM SUPPLIED FROM SAID SUPPLY PORTS FORMS ACONTINUOUS FILM OF MEDIUM PRIOR TO BEING EXHAUSTED THROUGH SAID EXHAUSTPORTS, AND MEANS TO DIVIDE SAID CONTINUOUS FILM INTO A PLURALITY OFSEPARATE STREAMS UPON BEING EXHAUSTED.